Apparatus and method for making measurements in mobile telecommunications system user equipment

ABSTRACT

A method and apparatus for selecting cells in a mobile telecommunications system, the system comprising a network of a plurality of cells of a Universal Mobile Telecommunications Systems (UMTS) and a network of a plurality of cells of a second Radio Access Technology (RAT), the method comprising, at a user equipment device: when in UMTS mode, flagging in a neighbouring cell list stored on the user equipment device information for a cell of a second RAT which is known to be unsuitable for selection. Information from the neighbouring cell list information for the flagged cell may be removed, in particular for a limited period of time.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation application of co-pendingpatent application Ser. No. 12/267,412 filed Nov. 7, 2008, which is acontinuation of application Ser. No. 10/921,079 filed Aug. 18, 2004,(now U.S. Pat. No. 7,463,887 issued Dec. 9, 2008), the contents of whichare incorporated herein by reference.

BACKGROUND

1. Technical Field

This application relates to a dual mode mobile telecommunication devicein general (for instance a UMTS (Universal Mobile TelecommunicationsSystem) and GSM (Global System for Mobile Communications) dual modedevice), and to an apparatus and method for selecting cells in mobiletelecommunications system user equipment. The invention also relates toMobile Stations (MS) and User Equipment (UE) which support at least twoRadio Access Technologies (RATs).

2. Description of the Related Art

The approaches described in this section could be pursued, but are notnecessarily approaches that have been previously conceived or pursued.Therefore, unless otherwise indicated herein, the approaches describedin this section are not prior art to the claims in this application andare not admitted to be prior art by inclusion in this section.

In a typical cellular radio system, mobile user equipment (UE)communicates via a radio access radio network (RAN) to one or more corenetworks. User equipment (UE) comprises various types of equipment suchas mobile telephones (also known as cellular or cell phones), lap topswith wireless communication capability, personal digital assistants(PDAs) etc. These may be portable, hand held, pocket sized, installed ina vehicle etc and communicate voice and/or data signals with the radioaccess network.

The radio access network covers a geographical area divided into aplurality of cell areas. Each cell area is served by at least one basestation, which may be referred to as a Node B. Each cell is identifiedby a unique identifier which is broadcast in the cell. The base stationscommunicate at radio frequencies over an air interface with the UEswithin range of the base station. Several base stations may be connectedto a radio network controller (RNC) which controls various activities ofthe base stations. The radio network controllers are typically connectedto a core network.

UMTS is a third generation public land mobile telecommunication system.Various standardization bodies are known to publish and set standardsfor UMTS, each in their respective areas of competence. For instance,the 3GPP (Third Generation Partnership Project) has been known topublish and set standards for GSM (Global System for MobileCommunications) based UMTS, and the 3GPP2 (Third Generation PartnershipProject 2) has been known to publish and set standards for CDMA (CodeDivision Multiple Access) based UMTS. Within the scope of a particularstandardization body, specific partners publish and set standards intheir respective areas.

Consider a wireless mobile device, generally referred to as userequipment (UE), that complies with the 3GPP specifications for the UMTSand with GSM protocols. The 3GPP 25.331 specification, v.3.18.0,referred to herein as the 25.331 specification, addresses the subject ofthe Radio Resource Control (RRC) protocol specification. The 3GPP 25.304specification, v.3.14.0, referred to herein as the 25.304 specification,addresses the subject of UMTS User Equipment (UE) procedures in idlemode and procedures for cell reselection in connected mode between theUMTS Terrestrial Radio Access Network (UTRAN) and the UE.

Such a UE undertakes frequent measurement procedures. Clause 8.4 of the25.331 standard and its sub-clauses and clause 14 and its sub-clausesrelate to the measurement procedures to be undertaken by the UE as doclause 5 and its sub-clauses of the 25.304 specification. Both the25.331 standard (and in particular clause 8.4 and its sub-clauses andclause 14 and its sub-clauses) and the 25.304 standard (and inparticular clause 5.2.3.1 and its sub-clauses) are incorporated hereinby reference.

When camped on a UMTS cell, the UE shall regularly search for a bettercell according to the cell reselection criteria. If a better cell isfound, the UE should attempt to select that cell. A change of cell mayimply a change of RAT.

The 3GPP specificiations allow a dual-mode UE to repeatedly attempt tocamp on a cell using another RAT when the cell is known to beunavailable just because it happens to have the strongest availabletransmission signal.

For a dual-mode UE operating in UMTS idle mode (or CELL_PCH, URA_PCH orCELL_FACH states) and a GSM cell is initially found to be the best cell,problems can arise if the GSM cell is unsuitable or unavailable forselection, for example, if synchronization cannot be achieved or systeminformation cannot be decoded. Each unsuccessful attempt to reselect tothe unsuitable/unavailable GSM cell results in a short loss of service,and the UE will be unresponsive to attempts at incoming communication.It will therefore be seen that there is a need to avoid such repeatedinterruptions.

Further, battery power in the UE can also be wasted by repeated attemptsof the UE to change its operational mode between RATs every few seconds.With reference to clause 5.5.2.2.3 of the 3GPP 25.133 specification, v3.18.0, the minimum interruption time when attempting to move from aUMTS cell to a GSM cell is 40 ms, and is likely to be considerablylonger, perhaps even greater than 100 ms.

There are thus proposed strategies for User Equipment (UE) measurementprocedures, which are appropriate in UMTS idle mode and during cellreselection to a GSM cell. A number of such strategies are detailedbelow.

Other aspects and features of the present invention will become apparentto those ordinarily skilled in the art upon review of the followingdescription of specific embodiments of an apparatus and method forcarrying out User Equipment (UE) procedures in idle mode and proceduresfor cell reselection in connected mode.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the attached drawings, in which:

FIG. 1 shows an overview of a network and UE device;

FIG. 2 is a flow diagram illustrating a first embodiment of a processfor cell selection;

FIG. 3 is a flow diagram illustrating a second embodiment;

FIG. 4 is a block diagram illustrating an embodiment of a protocol stackapparatus provided with a RRC block, in accordance with the presentapplication; and

FIG. 5 is a block diagram illustrating a mobile device, which can act asa UE and co-operate with the apparatus and methods of FIGS. 1 to 5.

The same reference numerals are used in different figures to denotesimilar elements.

DETAILED DESCRIPTION OF THE DRAWINGS

A method and apparatus for making measurements in mobiletelecommunications system user equipment are described. In the followingdescription, for the purposes of explanation, numerous specific detailsare set forth in order to provide a thorough understanding of thepresent invention. It will be apparent, however, to one skilled in theart that the present invention may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form in order to avoid unnecessarily obscuring thepresent invention.

The needs identified in the foregoing Background, and other needs andobjects that will become apparent from the following description, areachieved by, in one aspect, a method for selecting cells in a mobiletelecommunications system, the system comprising a network of aplurality of cells and at least one user equipment device. The methodcomprises, at the user equipment device, when in UMTS mode, flagging ina neighboring cell list stored on the user equipment device informationfor a cell of a second RAT which is known to be unsuitable forselection.

In other aspects, the invention encompasses an apparatus and acomputer-readable medium configured to carry out the foregoing steps. Inparticular, the method may be implemented in a mobile telecommunicationsdevice, with or without voice capabilities, or other electronic devicessuch as handheld or portable devices.

There is also provided a method of maintaining information relating toselecting cells that are potentially suitable for a user equipment toselect/camp on in a telecommunications system, the system comprising anetwork of a plurality of cells of a Universal Mobile TelecommunicationsSystem and a network of a plurality of cells of a second Radio AccessTechnology (RAT), the system further comprising at least one userequipment device, the method comprising, at the user equipment device:storing information relating to cells of the network; from the storedmaintained information, identifying a cell which meets a cell selectioncriterion; determining whether the identified cell is of the other RAT;and, if the identified cell is determined to be of the other RAT:determining whether the identified cell is suitable for selection; andif the identified cell is not suitable, flagging the cell as beingunsuitable for selection.

FIG. 1 shows an overview of a network and a UE device. Clearly inpractice there may be many UE devices operating with the network but,for the sake of simplicity, FIG. 1 only shows a single UE device. Forthe purposes of illustration, FIG. 1 also shows a network having a fewcomponents. It will be clear to a person skilled in the art that inpractice a network will include far more components than those shown.

FIG. 1 shows an overview of the radio access network 702 (RAN) used in aUMTS system or a GSM network. The network 702 as shown in FIG. 1comprises three Radio Network Subsystems (RNS) 2. Each RNS has a RadioNetwork Controller (RNC) 4. Each RNS 2 has one or more Node B 6 whichare similar in function to a Base Transmitter Station of a GSM radioaccess network. User Equipment UE 700 may be mobile within the radioaccess network. Radio connections (indicated by the straight dottedlines in FIG. 1) are established between the UE and one or more of theNode Bs in the UTRAN.

The RNC 4 controls the use and reliability of the radio resources withinthe RNS 2. Each RNC 4 may also be connected to a 3G mobile switchingcenter 10 (3G MSC) and a 3G serving GPRS support node 12 (3G SGSN).

An RNC 4 controls one or more Node B's. An RNC plus its Node B'stogether make up an RNS 2. A Node B controls one or more cells. Eachcell is uniquely identified by a frequency and a primary scrambling code(primary CPICH in FDD, primary CCPCH in TDD).

Generally in UMTS a cell refers to a radio network object that can beuniquely identified by a UE from a cell identifier that is broadcastover geographical areas from a UTRAN access point. A UTRAN access pointis a conceptual point within the UTRAN performing radio transmission andreception. A UTRAN access point is associated with one specific celli.e., there exists one UTRAN access point for each cell. It is theUTRAN-side end point of a radio link. A single physical Node B 6 mayoperate as more than one cell since it may operate at multiplefrequencies and/or with multiple scrambling codes.

Section 5.2.6 of the 25.304 standard sets out the cell reselectioncriterion.

In the following description, reselection between cells operating in FDDmode and attempting to change to GSM mode will be considered. Howeverthe technique is also applicable in reselection between cells operatingin TDD mode and attempting to change to GSM mode. The technique is alsoapplicable for reselection between CDMA2000 cells/GSM cells/GPRS cells.

The Network Operator transmits in the UMTS cell to all UEs in the UMTScell, over the broadcast channel (BCCH), a GSM Neighbouring Cell list.Alternatively, the list is derived at the UE from informationtransmitted by the Network Operator. This list contains informationrelating to GSM cells which are adjacent to, or in the vicinity of, theUMTS cell in question.

Included in the GSM neighboring cell list is information relating to thetransmission frequency of each neighboring GSM cell respectively.Accordingly, the UE has prior knowledge, at least in one mode ofoperation, of all the frequencies at which the neighboring GSM cellstransmit. As such, the UE can scan these frequencies for signalstrengths of the respective GSM cells. Once the respective frequencieshave been scanned, the UE populates the GSM neighboring cell list withinformation relating to cell ranking according to the cell reselectioncriteria for each cell at its respective transmission frequency.

In a similar fashion, a UMTS neighboring cell list is transmitted orcompiled, thereby allowing the UE to have prior knowledge of thetransmission frequencies of the neighboring UMTS cells and to scan thesefrequencies accordingly. This list is populated with transmissionfrequency information in a similar fashion to the way it is carried outfor the GSM neighboring cell list.

The GSM neighboring cell list, as transmitted by the Network Operator,does not take into account the status of the GSM cells; i.e. a cell maybe temporarily barred but will still be listed in the GSM neighboringcell list.

As will be discussed below, when the UE has determined that a GSM cellis barred, the GSM cell is removed by the UE from the GSM neighboringcell list stored locally at the UE until expiry of a time interval,T_(barred). This time interval is configurable, but a suitable timeperiod may be 300 seconds. During this time period, T_(barred), the“barred” cell is not to be considered as a candidate for reselection bythe UE.

The GSM neighboring cell lists may contain GSM cells that are barred andwhich are to be removed from the lists until expiry of the timeinterval, T_(barred). Alternatively, there may be a list for containingdetails of cells which are barred and details of the barred/unsuitablecell is added to this list. The barred cells may keep their indices inthe list but no measurement is performed, i.e., no scan at the frequencyof that cell is made. The UE may re-read and/or re-build the GSMneighboring cell list upon expiry of the time interval T_(barred) forthe or all barred cells, if more than one barred cell is found. Thetime, T_(barred), may be set individually for each barred cell.

A process of a cell reselection process is illustrated in FIG. 2 whichis a flow chart illustrating the operation of a UE device. At intervalsthe UE device carries out measurements, step 200. The UE carries outmeasurements on neighboring cells according to its capability.

The UE then determines whether the measurement data meets apredetermined criterion and stores the measurement data in an orderrelative to the meeting of the criterion (a cell ranking list). Anexample of the cell reselection criteria is given in 5.2.6 of the 25.304specification.

Table 1 shows an example of the signal measurement results for a UE,with the highest ranked cells being shown at the top of the table andthe lowest ranked cells shown at the bottom.

TABLE 1 C_(A) f₁ GSM C_(D) f₇ GSM C_(B) f₂ UMTS C_(E) f₈ GSM C_(F) f₃UMTS C_(G) f₄ GSM C_(C) f₅ GSM C_(I) f₆ GSMwhere C_(A) indicates a signal from cell A, f₁ indicates a signal atfrequency f₁, GSM indicates that the cell is a GSM cell and UMTSindicates that the cell is a UMTS cell. Typically, signal measurementresults for the GSM network and for the UMTS network are compiled inseparate tables for each network and a comparison or consolidationbetween the two tables is made prior to determination of the highestranked cell. However, for the sake of simplicity in this and followingexamples a consolidated table of results will be used.

When compiling the ranking list of the various neighboring GSM and UMTScells, the time period for the comparison between GSM cells and UMTScells is configurable; for further details see clause 5.2.6 of the25.304 specification.

The UE uses these measurement results to identify the highest rankedcell, step 202. In the example shown in table 1 this is the signal fromGSM cell A at frequency f₁. The UE then checks whether the identifiedcell at the identified frequency is suitable, step 204. If theidentified cell at the identified frequency is suitable, step 206,successful cell reselection has occurred, step 208, and the UE continuesoperation. However the identified cell may not be suitable. For example,if the system information from a cell which informs the UE how toconnect to the cell has an error in it, then the cell is deemed to beunsuitable.

However if the identified cell is not suitable at step 206, the UE thenflags the identified cell as unsuitable, step 207, for instance using anidentifier, or removes the unsuitable cell from the neighboring celllist. The cell may be flagged as unsuitable, to leave vacant theinformation relating to the unsuitable cell from the maintainedneighboring cell list. The UE then proceeds to identify the next highestranked cell, step 210. In the example shown in table 1, this is GSM cellD at a frequency f₇ i.e., a different GSM cell operating at a differentfrequency as the previously identified cell. The UE then attempts toconnect with this identified cell at step 204 and if successful asuccessful cell connection with GSM cell D at frequency f₇ is made.Otherwise the UE continues to identify the next highest ranked cells andto attempt to connect with these cells until a successful connection ismade or connection to all potential cells has failed, in which case theUE returns a message to the user, for instance “emergency calls only” or“no network coverage”.

The UE then periodically repeats the search for a suitable cell omittingfrom the search any cells which are flagged as unsuitable. Thus, if aGSM cell is not suitable or is barred, the UE does not repeatedlyattempt to camp on to the unsuitable/barred cell.

If the UE selects UMTS cell B because GSM cells A and D are unsuitable,then during the next cell reselection evaluation, cells A and D areexcluded from the next cell reselection process. Thus, if the GSM cellis not suitable or barred, the UE does not repeatedly attempt to camp onto the unsuitable/barred cell.

Note that the process may also be carried out without identifying thehighest ranked cell (i.e., steps 200, 202 and 210 may be omitted). Inthis case, the UE, when in UMTS mode, flags in a neighboring cell liststored on the user equipment device information for a cell of the secondRAT which is known to be unsuitable for selection.

In an embodiment of the invention, when an identified cell is deemedunsuitable, it is omitted from the GSM neighboring cell list.Alternatively, the identified cell can be added to a list of cells knownto be unsuitable. During the next reselection evaluation, the UEperforms measurements on cells listed in the GSM neighboring cell listbut omits the cell previously identified as the unsuitable/barred cell.

FIG. 3 shows a further embodiment of the technique. In this embodiment,the UE carries out measurements to search for the highest ranked cell ineach cell type (i.e. GSM or UMTS) required according to itscapabilities, step 302. An example of the measurements made by a UE isshown in table 2, with the highest ranked cells being shown at the topof the table and the lowest ranked cells shown at the bottom.

TABLE 2 C_(A) f₁ GSM C_(D) f₇ GSM C_(B) f₂ UMTS C_(E) f₈ GSM C_(F) f₃UMTS C_(G) f₄ GSM C_(C) f₅ GSM C_(I) f₆ GSM

The UE then identifies the highest ranked cell, step 304. For theresults shown in table 2, this is cell A (which happens to be a GSMcell) at frequency f₁. The UE then performs a check that this is a GSMcell, step 305 and, if the check confirms that this is a GSM cell, theUE checks if this identified GSM cell is suitable, step 306. (If, atstep 305 the UE determines that the cell is another UMTS cell, theprocess according to this embodiment of the invention terminates, step307, as reselection of a same RAT cell is not the focus of the presentdiscussion.) If the GSM cell is suitable, step 308, a successful cellreselection is made, step 310. However, if the cell is not suitablebecause it is barred for any reason (e.g. it is not suitable owing tocell information (for example because the cell is not on the same publicland mobile network (PLMN) as that selected by the UE)), or notavailable because of transmission problems (such as synchronizationcannot be achieved/system information cannot be decoded) step 312, thecell is barred as a candidate for reselection for the time T_(barred),step 315. If there are cells left to check in Table 2, step 313, the UEthen identifies the next highest ranked cell (frequency f₇, cell D),step 314, and checks if this is a GSM cell again, step 305. The processcontinues round the loop as above until successful cell reselection 310takes place, or a re-scanning step 302 is required. When the rescan step302 does take place, the UE removes details of the barred cell from thetable for the time T_(barred). As such, the barred cell is notconsidered as a candidate for reselection for this time interval. The UEmay check for remaining identified cells (step 313) before starting thenew cell reselection measurement. If a suitable cell is found then it isselected and the cell reselection evaluation process is started on thenew cell.

This continues until a suitable cell is identified, the next bestavailable cell is a UMTS cell or connection to all potential cells hasfailed, in which case the UE returns a message to the user, for instance“emergency calls only” or “no network coverage”. The UE thenperiodically searches for a suitable cell.

When a GSM cell is deemed unsuitable, for whatever reason, the cell inquestion can be explicitly removed (barred) from the cell reselectionmeasurements for a defined period of time as soon as it is determinedthat it is unsuitable or barred. During this time period, the cell willnot be considered as a candidate for cell reselection.

Examples of the second RAT are GSM, GPRS or CDMA2000. The following areexamples of barred or unsuitable cells: a cell with an “Intra-frequencycell-reselection indicator” set to “not allowed”; or a cell in which aservice is not available, such as an emergency call service, a dataservice (such as a packet data service e.g. GPRS or email).

Referring to the drawings, FIG. 4 is a block diagram illustrating anembodiment of a UMTS protocol stack apparatus.

The RRC block 136 a sub layer of Layer 3 130 of a UMTS protocol stack100. The RRC 136 exists in the control plane only and provides aninformation transfer service to the non-access stratum NAS 134. The RRC136 is responsible for controlling the configuration of radio interfaceLayer 1 110 and Layer 2 120. When the UTRAN wishes to change the UEconfiguration it will issue a message to the UE containing a command toinvoke a specific RRC procedure. The RRC 136 layer of the UE decodesthis message and initiates the appropriate RRC procedure. Generally whenthe procedure has been completed (either successfully or not) then theRRC sends a response message to the UTRAN (via the lower layers)informing the UTRAN of the outcome. It should be noted that there are afew scenarios where the RRC will not issue a response message to theUTRAN and, in those cases the RRC need not and does not reply. Cellreselection may be implemented in the RRC.

Turning now to FIG. 5, FIG. 5 is a block diagram illustrating a mobiledevice, which can act as a UE and co-operate with the apparatus andmethods of FIGS. 1 to 4, and which is an exemplary wirelesscommunication device. Mobile station 700 is preferably a two-waywireless communication device having at least voice and datacommunication capabilities. Mobile station 700 preferably has thecapability to communicate with other computer systems on the Internet.Depending on the exact functionality provided, the wireless device maybe referred to as a data messaging device, a two-way pager, a wirelesse-mail device, a cellular telephone with data messaging capabilities, awireless Internet appliance, or a data communication device, asexamples.

Where mobile station 700 is enabled for two-way communication, it willincorporate a communication subsystem 711, including both a receiver 712and a transmitter 714, as well as associated components such as one ormore, preferably embedded or internal, antenna elements 716 and 718,local oscillators (LOs) 713, and a processing module such as a digitalsignal processor (DSP) 720. As will be apparent to those skilled in thefield of communications, the particular design of the communicationsubsystem 711 will be dependent upon the communication network in whichthe device is intended to operate. For example, mobile station 700 mayinclude a communication subsystem 711 designed to operate within theMobitex™ mobile communication system, the DataTAC™ mobile communicationsystem, GPRS network, UMTS network, or EDGE network.

Network access requirements will also vary depending upon the type ofnetwork 702. For example, in the Mobitex and DataTAC networks, mobilestation 700 is registered on the network using a unique identificationnumber associated with each mobile station. In UMTS and GPRS networks,however, network access is associated with a subscriber or user ofmobile station 700. A GPRS mobile station therefore requires asubscriber identity module (SIM) card in order to operate on a GPRSnetwork. Without a valid SIM card, a GPRS mobile station will not befully functional. Local or non-network communication functions, as wellas legally required functions (if any) such as “911” emergency calling,may be available, but mobile station 700 will be unable to carry out anyother functions involving communications over the network 702. The SIMinterface 744 is normally similar to a card-slot into which a SIM cardcan be inserted and ejected like a diskette or PCMCIA card. The SIM cardcan have approximately 64K of memory and hold many key configuration751, and other information 753 such as identification, and subscriberrelated information.

When required network registration or activation procedures have beencompleted, mobile station 700 may send and receive communication signalsover the network 702. Signals received by antenna 716 throughcommunication network 702 are input to receiver 712, which may performsuch common receiver functions as signal amplification, frequency downconversion, filtering, channel selection and the like, and in theexample system shown in FIG. 7, analog to digital (A/D) conversion. NDconversion of a received signal allows more complex communicationfunctions such as demodulation and decoding to be performed in the DSP720. In a similar manner, signals to be transmitted are processed,including modulation and encoding for example, by DSP 720 and input totransmitter 714 for digital to analog conversion, frequency upconversion, filtering, amplification and transmission over thecommunication network 702 via antenna 718. DSP 720 not only processescommunication signals, but also provides for receiver and transmittercontrol. For example, the gains applied to communication signals inreceiver 712 and transmitter 714 may be adaptively controlled throughautomatic gain control algorithms implemented in DSP 720.

Mobile station 700 preferably includes a microprocessor 738 whichcontrols the overall operation of the device. Communication functions,including at least data and voice communications, are performed throughcommunication subsystem 711. Microprocessor 738 also interacts withfurther device subsystems such as the display 722, flash memory 724,random access memory (RAM) 726, auxiliary input/output (I/O) subsystems728, serial port 730, keyboard 732, speaker 734, microphone 736, ashort-range communications subsystem 740 and any other device subsystemsgenerally designated as 742.

Some of the subsystems shown in FIG. 5 perform communication-relatedfunctions, whereas other subsystems may provide “resident” or on-devicefunctions. Notably, some subsystems, such as keyboard 732 and display722, for example, may be used for both communication-related functions,such as entering a text message for transmission over a communicationnetwork, and device-resident functions such as a calculator or tasklist.

Operating system software used by the microprocessor 738 is preferablystored in a persistent store such as flash memory 724, which may insteadbe a read-only memory (ROM) or similar storage element (not shown).Those skilled in the art will appreciate that the operating system,specific device applications, or parts thereof, may be temporarilyloaded into a volatile memory such as RAM 726. Received communicationsignals may also be stored in RAM 726.

As shown, flash memory 724 can be segregated into different areas forboth computer programs 758 and program data storage 750, 752, 754 and756. These different storage types indicate that each program canallocate a portion of flash memory 724 for their own data storagerequirements. Microprocessor 738, in addition to its operating systemfunctions, preferably enables execution of software applications on themobile station. A predetermined set of applications that control basicoperations, including at least data and voice communication applicationsfor example, will normally be installed on mobile station 700 duringmanufacturing. A preferred software application may be a personalinformation manager (PIM) application having the ability to organize andmanage data items relating to the user of the mobile station such as,but not limited to, e-mail, calendar events, voice mails, appointments,and task items. Naturally, one or more memory stores would be availableon the mobile station to facilitate storage of PIM data items. Such PIMapplication would preferably have the ability to send and receive dataitems, via the wireless network 702. In a preferred embodiment, the PIMdata items are seamlessly integrated, synchronized and updated, via thewireless network 702, with the mobile station user's corresponding dataitems stored or associated with a host computer system. Furtherapplications may also be loaded onto the mobile station 700 through thenetwork 702, an auxiliary I/O subsystem 728, serial port 730,short-range communications subsystem 740 or any other suitable subsystem742, and installed by a user in the RAM 726 or preferably a non-volatilestore (not shown) for execution by the microprocessor 738. Suchflexibility in application installation increases the functionality ofthe device and may provide enhanced on-device functions,communication-related functions, or both. For example, securecommunication applications may enable electronic commerce functions andother such financial transactions to be performed using the mobilestation 700.

In a data communication mode, a received signal such as a text messageor web page download will be processed by the communication subsystem711 and input to the microprocessor 738, which preferably furtherprocesses the received signal for output to the display 722, oralternatively to an auxiliary I/O device 728. A user of mobile station700 may also compose data items such as email messages for example,using the keyboard 732, which is preferably a complete alphanumerickeyboard or telephone-type keypad, in conjunction with the display 722and possibly an auxiliary I/O device 728. Such composed items may thenbe transmitted over a communication network through the communicationsubsystem 711.

For voice communications, overall operation of mobile station 700 issimilar, except that received signals would preferably be output to aspeaker 734 and signals for transmission would be generated by amicrophone 736. Alternative voice or audio I/O subsystems, such as avoice message recording subsystem, may also be implemented on mobilestation 700. Although voice or audio signal output is preferablyaccomplished primarily through the speaker 734, display 722 may also beused to provide an indication of the identity of a calling party, theduration of a voice call, or other voice call related information forexample.

Serial port 730 in FIG. 5, would normally be implemented in a personaldigital assistant (PDA)-type mobile station for which synchronizationwith a user's desktop computer (not shown) may be desirable, but is anoptional device component. Such a port 730 would enable a user to setpreferences through an external device or software application and wouldextend the capabilities of mobile station 700 by providing forinformation or software downloads to mobile station 700 other thanthrough a wireless communication network. The alternate download pathmay for example be used to load an encryption key onto the devicethrough a direct and thus reliable and trusted connection to therebyenable secure device communication.

Other communications subsystems 740, such as a short-rangecommunications subsystem, is a further optional component which mayprovide for communication between mobile station 700 and differentsystems or devices, which need not necessarily be similar devices. Forexample, the subsystem 740 may include an infrared device and associatedcircuits and components or a Bluetooth™ communication module to providefor communication with similarly enabled systems and devices.

Extensions and Alternatives

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the scope of the technique. The specification anddrawings are, accordingly, to be regarded in an illustrative rather thana restrictive sense.

It is to be noted that the methods as described have shown steps beingcarried out in a particular order. However, it would be clear to aperson skilled in the art that the order of some of the steps may beimmaterial with respect to the operation of the method. The ordering ofthe steps as described herein is not intended to be limiting.

It is also to be noted that where a method has been described it isintended that protection is also sought for a device arranged to carryout the method and where features have been claimed independently ofeach other these may be used together with other claimed features.

1. A method of cell reselection by a user equipment device (UE), the UEconfigured to be operable with a first cellular Radio Access Technology(RAT) and a second cellular RAT, the method comprising: when the UE iscamped on a cell of the first RAT: the UE not considering as a candidatefor reselection a cell of a second RAT which is not suitable, andfurther not considering said cell of the second RAT as a candidate forreselection for a specified time period.
 2. The method according toclaim 1, further comprising considering said cell of the second RAT as acandidate for reselection after expiry of the specified time period. 3.The method according to claim 1, wherein not considering said cell ofthe second RAT comprises removing said cell from a list of neighboringcells.
 4. The method according to claim 1, wherein not considering saidcell of the second RAT comprises flagging said cell in a list ofneighboring cells as being unsuitable for selection.
 5. The methodaccording to claim 1, wherein said cell of a second RAT is not suitablewhen it is barred.
 6. The method according to claim 1, wherein said cellof a second RAT is not suitable due to being part of a list of barredcells.
 7. The method according to claim 1, wherein said cell of a secondRAT is not suitable due to being part of a list of unsuitable cells. 8.The method according to claim 1, wherein said cell of a second RAT isnot suitable due to belonging to a public land mobile network (PLMN)that is not the same as a PLMN selected by the UE.
 9. The methodaccording to claim 1, wherein the specified time period is a maximum of300 seconds.
 10. The method according to claim 1, wherein the specifiedtime period is 300 seconds.
 11. The method according to claim 1, whereinthe specified time period is a defined period of time.
 12. The methodaccording to claim 1, wherein the specified time period is a limitedperiod of time.
 13. The method according to claim 1, wherein the UEreceives a list of neighboring cells including the cell of the secondRAT.
 14. The method of claim 1, wherein the first RAT is selected from agroup including UMTS, GSM, or CDMA; and the second RAT is different fromthe first RAT and selected from the group including UMTS, GSM, or CDMA.15. A method of cell reselection by a user equipment device (UE), the UEconfigured to be operable with a first cellular Radio Access Technology(RAT) and a second cellular RAT, the method comprising: when the UE iscamped on a cell of the first RAT: the UE not considering as a candidatefor reselection a cell of a second RAT which is not suitable, andfurther not considering said cell of the second RAT as a candidate forreselection for a configurable time period.
 16. A user equipment device(UE) configured to be operable with a first cellular Radio AccessTechnology (RAT) and a second cellular RAT, the UE comprising: aprocessor and memory, the UE being operable so that, when the UE iscamped on a cell of the first RAT: the UE not considering as a candidatefor reselection a cell of a second RAT which is not suitable, andfurther not considering said cell of the second RAT as a candidate forreselection for a specified time period.
 17. The device according toclaim 16, wherein the UE is configured to consider said cell of thesecond RAT as a candidate for reselection after expiry of the specifiedtime period.
 18. The device according to claim 16, wherein, in order tonot consider said cell of the second RAT, the UE is configured to removesaid cell from a list of neighboring cells.
 19. The device according toclaim 16, wherein, in order to not consider said cell of the second RAT,the UE is arranged to flag said cell in a list of neighboring cells asbeing unsuitable for selection.
 20. The device according to claim 16,wherein said cell of a second RAT is not suitable when it is barred. 21.The device according to claim 16, wherein said cell of a second RAT isnot suitable due to being part of a list of barred cells.
 22. The deviceaccording to claim 16, wherein said cell of a second RAT is not suitabledue to being part of a list of unsuitable cells.
 23. The deviceaccording to claim 16, wherein said cell of a second RAT is not suitabledue to belonging to a public land mobile network (PLMN) that is not tothe same as a PLMN selected by the UE.
 24. The device according to claim16, wherein the specified time period is a maximum of 300 seconds. 25.The device according to claim 16, wherein the specified time period is300 seconds.
 26. The device according to claim 16, wherein the specifiedtime period is a defined period of time.
 27. The device according toclaim 16, wherein the UE receives a list of neighboring cells includingthe cell of the second RAT.
 28. The device of claim 16, wherein thefirst RAT is selected from a group including UMTS, GSM, GPRS or CDMA;and the second RAT is different from the first RAT and selected from thegroup including UMTS, GSM, GPRS or CDMA.
 29. The device of claim 16,wherein the reselection is for camping.
 30. A user equipment device (UE)configured to be operable with a first cellular Radio Access Technology(RAT) and a second cellular RAT, the UE comprising: a processor andmemory, the UE being operable so that, when the UE is camped on a cellof the first RAT: the UE not considering as a candidate for reselectiona cell of a second RAT which is not suitable, and further notconsidering said cell of the second RAT as a candidate for reselectionfor a configurable time period.